and Laboratory Methods. 2415 



The Technique of Biological Projection and Anesthesia of 



Animals. 



Copyrighted. 



XV. THE TECHNIQUE OF COLLECTING, MOUNTING, AND PROJECTING 

 LIVE PLANTS AND ANIMALS. 



This part of our subject presupposes a working knowledge of the essentials 

 of projection microscopes and of the methods of anesthetizing animals, as 

 described in the preceding articles of this series. We are now to consider in 

 detail the kinds of apparatus needed for collecting, keeping alive, and mounting 

 various types of small live organisms, the methods of using the apparatus so as 

 to attain the best results with the expenditure of a minimum amount of time, 

 and the difficulties to be overcome in manipulating the mounted specimens on 

 the projection microscope. The work is not difficult and the results are both 

 interesting and valuable. A large number of species of small aquatic animals, 

 not usually studied in zoological courses but especially serviceable in this work, 

 may be readily collected along with the species more commonly studied. 



AQUATIC SPECIES. 



These are found in greatest variety and abundance among submerged plants 

 in slow streams, ponds, and lakes. The stock of live material for winter work 

 should be collected in late summer or early fall, and is easily obtained with a 

 simple outfit consisting of a strong fishing rod from eight to twelve feet long 

 with a strong screw-hook of medium size securely fastened at its tip ; a flat bot- 

 tomed basket filled with six or more glass fruit cans, without covers, and several 

 wide-mouthed bottles of different sizes ; a pocket magnifier with lenses of from 

 two to four inches focal length ; a wide-mouthed bottle or slender beaker holding 

 about half a pint, made of such clear glass that small animals may be easily 

 seen through its sides, and fitted with a bail of strong cord ; a pocket knife with 

 a sharp blade of medium or large size ; and a fine-mesh wire strainer about four 

 inches in diameter, or a fine net of about the same size, which may be attached 

 to the tip of the pole and easily removed when the hook is to be used. Dealers 

 in house furnishings sell wire strainers of different sizes, and, in addition to the 

 above, a small one about one and a half inches in diameter having a very fine 

 mesh and a rigid handle is a most useful piece of apparatus for removing small 

 and active animals from aquaria in the laboratory. Such an outfit is easily 

 carried on a bicycle. 



On arriving at a pond or sluggish stream find a place where submerged water 

 plants, especially the common water-weed {Elodea or Anacharis canadensis), are 

 abundant and fill the beaker with clear water. If the shore is soft and wet, the 

 beaker may be hung by its bail on the screw hook and dipped into the water and 

 set aside ready for use. Reach well down to the base of the stems of the water 

 plants with the hook and firmly but gently pull them up, draw them to shore 

 and immediately place all or a part of them in the beaker of water. It is usually 



